Drinkers could soon be enjoying a new type of alcoholic beverage after Japanese scientists said they have invented a way to produce booze from wood.

Researchers from Japan's Forestry and Forest Products Research Institute have been testing the method of producing drinkable alcohol - known as ethanol - since June 2009.

Now they say the drinks they are making from tree bark are similar to drinks aged in wooden barrels, and could be served to customers by 2021.

To make the drinks, the scientists had to pulverise the tree bark into a paste, then hydrolysed it with a commercial cellulase enzyme to obtain sugar from it.

This sugar was fermented using yeast, and, by avoiding a manufacturing process which involves the heat, the scientists say they have been able to let the alcohol retain the flavour of the trees it is made from.

Both brewed and distilled versions of drinks made from cedar, birch and cherry have been made, with 4kg (8.8lb) of cedar wood giving them 3.8 litres (eight pints) of booze with an alcohol content of 15% - similar to the rice-wine sake.

Image:The alcohol could be made from any of Japan's famous trees

One of the team, Kengo Magara, told the AFP news organisation that the distilled alcohol appeared to be the better drink to the researchers.

He said that while the scientists had already produced biofuel by fermenting wood, that fuel contained toxins and was flavourless, making it unsuitable for human consumption.

"But our method can make it drinkable, and with a wood flavour, because it does not require high heat or sulphuric acid to decompose the wood," Mr Magara said.

Japan's Forestry and Forest Products Research Institute has a large remit to study the country's woods and forests, but Mr Magara acknowledged to AFP that inventing a new form of booze was a little unusual.

"We thought it would be interesting to think that alcohol could be made from something around here like trees," he said.